Electric Boilers & Heat Control

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matt_b
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Electric Boilers & Heat Control

Post by matt_b »

So I'm using a Still Spirits T500 electric boiler with a copper pot still head. Electric is handy for me, since during winter I'm distilling in my basement sometimes. I'll attach a pic of my very basic rig to the post. But I'm curious just how much attention experienced folks pay to the temperature of the vapor in the condenser. Still Spirits makes a very big deal of keeping a steady temperature in the manuals that came with my boiler and still head. And all three books I've read on distilling seem to place a lot of importance on temperatures as well. With an electric though, I'm kind of along for the ride. With a pot still head is this ok, or should I build a voltage regulator and try to hold the vapor temp smack in "hearts range" for as long as possible? I've read everything from "just take it all in small containers and mix later" to the SP manuals which have laser focus on keeping the temp steady.

Building a regulator would be easy enough for an old Navy electrician (yeah, my last name is Barnickle... no kiddin'). But I'm curious if it's of value, or if I'm making it to danged hard.
T500 with copper head
T500 with copper head
Advice appreciated.
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Re: Electric Boilers & Heat Control

Post by As-Ol-Joe »

I built a PID controller for my still. You can set the temperature where ever you want it and it will normally stay within about 2 degrees of your set point. I normally start out with a temperature of 185 degrees and run off 100 ml, then raise my temperature in increment of 2 degrees until I get to 199 degrees. I let it sit there for the rest of the run. As the alcohol cooks out the temperature will raise to about 201 degrees. That is when I shut it down.

To me, vapor temperature tells the tale.
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Re: Electric Boilers & Heat Control

Post by Yummyrum »

Trying to control temp is a complete waste of time in a pot still . The wash will boil at a temp determined by the mix in the boiler at the time .
Sure pure ethanol boils at 78.3°C and water boils at 100°C but you have a mix of the two plus a whole lot of other stuff .The boil point will be somewhere in between .

Yes temp is important in a reflux still ..... not a pot still .
More importantly you need to adjust the power to the boiler so that the stream is about the size of a pencil lead ..... and yes you need to collect it in small jars , let them air overnight and make cuts .
If you take off too hard then you will smear the tails through the run .
I agree that 2000 watts is too much power for a spirit run and a controller is required for that size of boiler but it would be fine as is for stripping runs
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Re: Electric Boilers & Heat Control

Post by Saltbush Bill »

matt_b wrote: Still Spirits makes a very big deal of keeping a steady temperature in the manuals that came with my boiler and still head. And all three books I've read on distilling seem to place a lot of importance on temperatures as well.
Your better off forgetting most of what Stillspirits says.
matt_b wrote:and try to hold the vapor temp smack in "hearts range" for as long as possible?

G'day Matt, This is a part of distilling that a lot of newbies have trouble coming to grips with, you can not control the temperature of what the wash in your boiler boils at , nor can you control the temp of the vapor anywhere in the still.
The only thing you can control is how much power / heat you put into the boiler, or in other words how hard the wash boils.
Water as an example boils at 100c or 212F , no matter if you use a small flame to make it boil slowly or a huge flame to make it boil really fast it wont change the temp it will still boil at 100c or 112F. What you are changing is how much vapor is coming of the water ..or how fast it is evaporating.
Ethanol boils at 78.37 °C or 173F again no matter how hard or slow you boil it you can not change the boiling temp.
To add to this problem your wash isn't water or ethanol its a mix those and a pile of other things that all have different boiling points.
As an example
Acetone 56.5C
Methanol 64C
Ethyl acetate 77.1C
Ethanol 78C
2-Propanol 82C
1-Propanol 97C
Water 100C
What is the boiling point of that mixture ? I don't know...I don't care and I don't need to know.
What you do need to know is that as the lighter of those compounds with the lowest boiling points leave the boiler your wash temp and vapor temp will go up. In short your wash and vapor temp is never the same, its always increasing as the run goes on.
Now back to your boiler ...to get the best from your pot head you really should build or buy some sort of controller. There are plans on this site if you search, word of mouth is that still dragon sell good reliable kits at a reasonable price.
Once you have a controller you can control the speed at which the product leaves the business end of your pot still and that will give you the most control over what leaves your still and when.
Good luck , hope I haven't confused you to much.
Edit Yummy beat me to it ..could have saved all that typing ...he said it better in fewer words anyway.
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Re: Electric Boilers & Heat Control

Post by acfixer69 »

As-Ol-Joe wrote:I built a PID controller for my still. You can set the temperature where ever you want it and it will normally stay within about 2 degrees of your set point. I normally start out with a temperature of 185 degrees and run off 100 ml, then raise my temperature in increment of 2 degrees until I get to 199 degrees. I let it sit there for the rest of the run. As the alcohol cooks out the temperature will raise to about 201 degrees. That is when I shut it down.

To me, vapor temperature tells the tale.
I don't know how you got to that conclusion that temperature is a factor in driving a pot still. The flow rate or take off speed is what matters. Power to the boiler will determine that speed.

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Re: Electric Boilers & Heat Control

Post by As-Ol-Joe »

You are right. I use a packed column. Sorry.
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Re: Electric Boilers & Heat Control

Post by zapata »

As-Ol-Joe wrote:You are right. I use a packed column. Sorry.
Doesnt matter. You are using a pid to do something poorly that happens perfectly automagically. I can only guess you havent run your still much without a pid?

It is the mixture in the pot and atmospjeric pressure that determines boiling point. Not your pid. It is the mixture in the pot, column design, packing and reflux rate that determines the vapor temp in any location of a column, not a pid. If your temp probe is in the pot all you are doing is stopping the pot from boiling whenever your pid makes the temp in the pot below whatever temp it boils at. A steady heat input would show the exact same change in pot temperature through the run, but in steady natural changes instead of the constant small on/off your pid does and the larger steps of your timing protocol.

If your temp probe is in the column, it is equally useless. At equilibrium with a steady power input the lowest boiling compoments (or their azeotropes) will all rise to the top, and stack in order down the column. A pid can only interfere.

On a reflux still a pid is actually more of a detriment than in a potstill. Everytime the pot stops boiling because of your pid or timing protocol, your reflux rate drops to zero. It is the reflux which does the brunt of the rectifying in a reflux still. It's right there in the name, why would you want to kill your reflux so many times through a run?

Run without pid, a steady power input and a takeoff rate that doesnt disturb the column equilibrium and you will get purer product and faster runs. And not with 2 degree or whatever accuracy, but with pinpoint infinite significant figures precision, reduced only by how slowly you are willing to takeoff.

Obviously you CAN do it as you say, but physics dictate that what you think is happening is not. Not trying to bust your balls, its a mistake many of us have made.

The only place for a pid in a still would be to automatically bring it to near boiling temp, then shut off the pid function and switch to steady power management. Which is exactly what the only commercial pid for stills I've ever seen does, available from auberins.

I've read theoretical discussion you could use a pid to control a valve on product takeoff not boiler control. I don't think anyone has actually bothered trying because a simple open/closed valve controlled by a .1 degree probe accomplishes the task perfectly well if the probe is appropriately located in the column.
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Re: Electric Boilers & Heat Control

Post by As-Ol-Joe »

I run a full size chemical distillation process for a living. Stripping column is 75 ft tall, reflux column is 85 ft tall with a 40 ft condenser. All instrumentation is PID controlled and no input or output are rock steady. My final product is 99.5%.

Temperature and pressure are everything. I can look at temp and pressure and tell within .5% what the purity is.

In home distilling with no pressure, the correlation between temperature and purity are still relevant.
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Re: Electric Boilers & Heat Control

Post by zapata »

Well that is a totally different beast. And to be honest, it seems disingenuous to compare a home reflux rig to an industrial plant. A simple pid controlling the boiler on anything like a typical home setup will behave as I described. With your work experience you should understand that, heck even seen it happen. Either you have more going on than a single pid on a typical still, or you'd be better off without it.

If you do have more going on, then I'd love to hear or see more details about it, assuming the OP doesn't mind the diversion.
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Re: Electric Boilers & Heat Control

Post by Saltbush Bill »

This is gunna get interesting ..I'll call bullshit that you can run a hobby size still the same way.
Joe is it a possibility that you have spent so much time looking at that computer screen that you don't even understand the principles of distillation at a hobby level ?
As-Ol-Joe wrote:My final product is 99.5%.
This in its self tells me that you and I live in two different worlds :thumbup:
Unless your running some sort of fancy vacuum still you have no hope of achieving that sort of %
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Re: Electric Boilers & Heat Control

Post by zapata »

If we give him the benefit of the doubt on the commercial plant, I assumed they are not rectifying ethanol. He never said they were and it could still be somewhat relevant experience. However doubt remains on the home rig.
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Re: Electric Boilers & Heat Control

Post by As-Ol-Joe »

99.5% is chemical purity.
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Re: Electric Boilers & Heat Control

Post by As-Ol-Joe »

matt_b, SCR's are less than $20 on Ebay.
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Re: Electric Boilers & Heat Control

Post by greggn »

> Advice appreciated.

Shockingly, no one offered this advice ... lose the plastic tubing on the condenser output.
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Re: Electric Boilers & Heat Control

Post by Yummyrum »

greggn wrote:> Advice appreciated.

Shockingly, no one offered this advice ... lose the plastic tubing on the condenser output.
Well spotted greggn :thumbup: ... too busy on pot still temp ranting to notice the nasty plastic :oops:

Regarding PID control of reflux stills , many successfully do this but generally its by controlling coolant flow through the Deflag on CM stills , not by controlling boiler power . An LM still could be controlled by a PID adjusting boiler power But OP is running a Pot still not a reflux still . :crazy:

Zapata ,I'll admit to being a bit of a electronics nerd but I totally agree with you on leaving controllers out of home distilling ... I prefer the automajic too :thumbup:
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Re: Electric Boilers & Heat Control

Post by matt_b »

Gents, thanks for the spirited responses, and wisdom where applicable. :mrgreen: I kinda shot a flair in the paint locker there eh? For my part I've found I can easily buy a controller online. But in the interest of taking the difficult path for no apparent reason I'm going to break out the books and build a voltage regulator, probably with bells and whistles no one would ever need. I'll let you know my experience with trying to control the automagical processes when I experience it. Or maybe you'll toast me at my wake when I electrocute myself.

Now I hang my head in shame for buying my entire setup online. :oops: If it helps I've been discussing building one with my Dad, for his man-cave/garage. That said, what's the beef with the PVC hose tubing at the condenser exit? I've always hated that damned thing, but having a flexible "something" there makes sense as I swap containers. What "should" I have at the condenser output? If you say "hard copper piping" I may have to give a snarky reply!

Cheers!
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Re: Electric Boilers & Heat Control

Post by acfixer69 »

How about soft copper tubing. PVC degrades with high ABV liquids and vapors and goes into your collection jar to be drank by people you care about and is a known carcinogenic.

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Re: Electric Boilers & Heat Control

Post by zapata »

Hey matt, I'm sorry I didn't really respond to you at all in your own thread, how rude! So, back to your OP, though I'll repeat a bit of what others have said.

Temperatures can be important to pay attention to. They do correlate to where you are in the run by being a good indicator of the strength of spirit coming off. But with a pot still you can not keep them steady, no matter what the instructions may say. So watch them or record them if you want, but you've got no influence on them with or without a controller.
Have you played with the calculators on the parent site? They give a very good indication of what happens on a pot still run. Go plug in some numbers for a hypothetical run in your still and see what the table looks like.
http://homedistiller.org/calcs/husker_pot_calc_v2.php" onclick="window.open(this.href);return false;" rel="nofollow
See how you specify a steady power to run at? That is what a controller is good for on a pot still, so you can set that power to where you want it, and typically leave it alone through the run. But even if you change the power during the run it won't change the temperature in either the pot or the still head, it will only change how quickly it progresses through the same temps. (change the power parameter on the calculator and see exactly that happen).
An SCR or SSR is good for this, and super easy to build. But you only need this if you are not happy with the heat input built into your still.

Looking at the table on that calculator also shows what I mean by automagical. The temperatures shown are dictated by the mixture of the liquid and resulting vapors. NOT power input. In the still you start with a moderate % of alcohol in water in the boiler, but the alcohol boils off faster than the water so the mixture in the pot continuously gets hotter as it's boiling point rises, automagically. The same happens at the still head, It gradually and continuously gets hotter as the concentration of alcohol in the vapor decreases.

The numbers are important to some people, especially beginners. A beginner wants to know something like "Heads will come off between A and B degrees, hearts from B to C, tails from C to D". Unfortunately that makes mediocre cuts at best, there are just too many variables between runs to know what temps the cuts should be at. The vast majority of us here are firm believers in collect everything in relatively small jars, air it out for a day or 2 and make the cuts by smell and taste. You can record the temps while you do this to have some idea of where to expect the changes to be, or to estimate the strength of each of the jars (average start and end temp for a jar, then look up what that vapor temp correlates to in terms of ABV), or to give you an idea what to expect in the future on an identical run. But after a while you will really finally accept that the numbers will be what they will be, and there is absolutely no NEED to ever look at that thermometer much less record it or *gasp* try to control it. I myself was stubborn and kept putting thermometers on my pot still through several rebuilds until I finally gave up. Haven't had one anywhere other than a boiler and coolant reservoir for years and haven't missed it at the still head all.

If you want bells and whistles on your controller, go for it. I'm actually not anti-bells and whistles at all. My current controller has a kill switch, GFCI protection, power on light, LCD and analog meters for amperage, voltage, wattage, time, amp hours and watt hours. I'm currently collecting parts to add in a NO relay to shut it down based on a coolant flow switch, vent temperature (for reflux), product temperature, dead man timer and spilled liquid around the collection area. Just for safety, yes even while I'm sitting within arms reach, I'd just like it to shut off if there is a problem without waiting for me to notice the vapor shooting out of it before a pilot light or compressor spark rudely notifies me. Since I do use the controller to make mashes from time to time, I may even add a PID! (I just know I can't use that during a distillation run).

Regarding your plastic tube, yeah, I know it's convenient, but it really isn't safe. Use stainless or copper or nothing. Put a sturdy stand or heck even an inverted bucket under it to set your jars on and you won't need a tube. You may find people on other sites or suppliers say silicone hose is safe (it's against the rules to say it here), but virtually nobody will tell you in good faith that PVC is ok for high proof spirits meant for consumption.
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Re: Electric Boilers & Heat Control

Post by Saltbush Bill »

zapata wrote:you will finally accept that the numbers will be what they will be,
No more needs to be said ........................that covers it so very very nicely :thumbup:
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Re: Electric Boilers & Heat Control

Post by Yummyrum »

Agree with that salty :thumbup:
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Re: Electric Boilers & Heat Control

Post by matt_b »

Thanks Zapata for the well considered reply. I've roughed out a controller for my boiler and will be doing a run with it in a couple of days, to see if it helps me out. But I find I like the idea of "auto-magical" a bit better. Just letting the still do it's work, making my cuts, and eventually learning what to taste and smell for. My temp-o-phobia really came from the still spirits manuals, all of which are hyper-focused on controlling temperature.

What's funny is, I'm sure I've read it in half a dozen posts. But it just registered that i should let my cuts sit for a bit before sorting and mixing them. Little light bulbs coming on with every run. : )
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Re: Electric Boilers & Heat Control

Post by matt_b »

Ok, I've done a few runs and found controlling the temp really doesn't help me much with regard to the end product. I think I'm won over to the "automagical" method, at least with the pot still. I have come up with half a dozen other questions though, so I'm going to peruse the forums here and find where to post them.

I produced something drinkable finally. I won't say it's great. But I'm starting to hope I'll get there.
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Re: Electric Boilers & Heat Control

Post by acfixer69 »

matt_b wrote:Ok, I've done a few runs and found controlling the temp really doesn't help me much with regard to the end product. I think I'm won over to the "automagical" method, at least with the pot still. I have come up with half a dozen other questions though, so I'm going to peruse the forums here and find where to post them.

I produced something drinkable finally. I won't say it's great. But I'm starting to hope I'll get there.
Well matt b you have taken the first step. carry on

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Re: Electric Boilers & Heat Control

Post by sampvt »

I am so confused reading all these posts, bar one, that seems to make sense. My two penneth and forgive me if my figures are out in terms of numbers to temp degrees.

If we put a 12 to 40% wash into a t500 then we know that most of that wash is water and we all know that acetone boils at 52' methanol at 56' ethanol at 76' and water at 100'.........once the boilers liquid reaches or approaches the temp ethanol escapes as vapour, the nasties have already gone so the foreshots and the heads are discarded leaving the hearts which are now dripping out the spout. For as long as there is ethanol in the boilers liquid, the temp of said liquid will remain at 78 or thereabouts, but when the hearts are all but gone and the tails start to turn up, so does the temp of the boiler until everything has vacated through the lym arm and condenser and we are left with water boiling at 100c.

My question therein is simple...WHY DO WE NEED TO CONTROL THE BOILERS TEMP. surely controlling the voltage does nothing more than slow the inevitable boil factors, just like using number 2 on the gas ring to simmer soup. Its still boiling but less power is being used. Sounds like a lesson or exercise in futility as far as I'm concerned, so can someone please put me right as I've got a t500 with both copper dome and reflux column but never used the dome as yet, but next week I will, hence my interest in the post.
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Re: Electric Boilers & Heat Control

Post by still_stirrin »

sampvt wrote: Thu Dec 03, 2020 5:44 amMy question therein is simple...WHY DO WE NEED TO CONTROL THE BOILERS TEMP...
Private Sam, you CAN’T control the boiler’s temperature unless it is filled with a PURE liquid, at which time setting the PiD at the boiling point of the pure liquid would only reach a simmer and produce very little, if any product at the outlet. You have to put ENERGY into the liquid to cause it to change state (from a liquid to a vapor). This is Physics 101. It’s the Law of the World! And guess what....you have to extract that energy in the product condenser to get it to change phase again (from a vapor to liquid condensate).

For a mixture, physics dictates that the boiling point of the mixture (at any given time) will be determined by the composition of the mixture, not any single constituent. However, because the fractions of some of the more volatile constituents are small, minuscule in fact, those volatiles will boil out of the boiler first (which puts them in the foreshots and heads cuts). This changes the remaining boiler charge’s composition....and the process continues seemlessly.

With the balance of the boiler charge being water and ethanol, the temperature (a simple scaler measuring tool of one property of the mixture at any moment in time) will rise from boiling point of the ethanol to the boiling point of pure water, again as the mixture ratio changes from %ABV. Like the extraction of volatiles, the alcohol is eliminated first (before the water) simply because it is the lesser volume of the mixture.

This physical understanding (understanding of the physics involved) creates the greatest confusion with inexperienced distillers.
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Re: Electric Boilers & Heat Control

Post by sampvt »

Thanks for that but on the private sam thing. The Sammy part is my name but the pvt does not mean private. 25 years ago I decided to go to Mexico to play on the Mexican and American pro tour circuit (Im a golf pro). I bought a penthouse suite (sounds expensive but it wasn't) in a seaside town called Puerto Vallarta on the west coast about 200 km above Acapulco. Hence the PVT addition. I lived there for 10 years before returning home with cancer but I've kept the same emails for 25 years now.
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